Phil, some time ago there was talk of possibly releasing a soft phone (PC based). Can you please update us on this? I can understand that you would want security and it might be an issue to authenticate the user to get the billing right, would it help to implement something like a USB key/dongle? Or it can only make free calls? Thanks.
In the mean time, you could use a 56k voice modem with some softphone software and connect the modem up to a voip<->analog gateway like one of the ones from their website. A bit of a long winded process but if it works :-)